Circuit interrupter



Nov. 15, 1949 Filed Sept. 14, 1944 w. M. LEEDS CIRCUIT INTERRUPTER 6Sheets-Sheet l WITNESSES:

Nov. 15, 1949 w, LEEDS 2,488,131

CIRCUIT INTERRUPTER Filed Sept. 14, 1944 6 Sheets-Sheet 2 WITNESSES:

l N V E N TO R M nf/vap M Z eeafa NOV. 15, 1949 w, LEEDS 2,488,131

CIRCUIT INTERRUPTER Filed Sept. 14, 1944 s Sheets-Sheet 3 M8 0 47 5 0 630 o o X *J v c% 35 35 0 O WITNESSES: INVENTOR Mh/hrap M Z eeaf NOV. 15,1949 w LEEDS 2,488,131

CIRCUIT INTERRUPTER Filed Sept. 14, 1944 6 Sheets-Sheet 4 F19: /Z. [64F197 /6, 77

35 a? g 75 i 3 O 5 +2 53 /35 0 5'2 WITNESSES: E6 INVENTOR 5Mhf/Vap/Wleeofs 4. 6w:

Nov. 15, 1949 w. M. LEEDS 2,488,131

CIRCUIT INTERRUPTER Filed Sept. 14, 1944 6 Shee'ts-Sheet 5 III )IIl/(IIIIIIIll/IIIYIIIIIIIIIIIlI/IIl/IIIIIIII/III/liIII/IIIIIIIIIIIIYIIlI/IIIII/III/Ill/I IIIIIIII ,II I

WITNESSES:

INVENTOR MhfflropMZeeQ i Patented Nov. 15, 1949 CIRCUIT INTERRUPTERWinthrop M. Leeds, Forest Hills, Pa., asslgnor to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation of PennsylvaniaApplication September 14, 1944, Serial No. 553,997

16 Claims.

This invention relates to circuit interrupters in general and, moreparticularly, to arc-extinguishing structures therefor.

My invention has particular application to circuit interrupters of theliquid-break type and for purposes of illustration my invention will bedescribed in connection with such a type of circuit breaker.

The operating arrangement which I use in connection with my invention isrelated to the oper-- ating arrangements described in United Statespatent application filed August 15, 1944, Serial No. 549,576, now U. S.Patent 2,477,810, issued August 2, 1949 to Winthrop M. Leeds and JamesM. Cumming; and United States patent application filed August 31, 1944,Serial No. 552,133, now U. S. Patent 2,465,240, issued March 22, 1949 toWinthrop M. Leeds, the foregoing applications being assigned to theassignee of the instant application,

A general object of my invention is to provide an improved circuitinterrupter in which interruption of the circuit therethrough isefiected more rapidly than has been achieved heretofore.

-A more specific object of my invention is to provide an improvedcircuit interrupter, in which the maximum break distance in a group ofserially connected contact gaps is obtained with a minimum overalllength.

Another object is to provide an improved circuit interrupter in whichthe ratio of insulation to conducting material in the lengthwisedirection is very high when the contacts are in the open circuitposition.

Another object is to provide an improved circuit interrupter in whichthe inertia of the rotating parts is reduced considerably over thatwhich results in using straight line moving parts.

Another object is to provide an improved arcextinguishing assemblage,comprising a plurality of arc-extinguishing units with improvedoperating means therefore.

Another object is to provide an improved circuit interrupter of theforegoing type in which, during the interruption of low currents, arelatively long pressure-generating arc is employed to efiect fluid flowtoward the interrupting arc.

Another object is to provide an improved circuit interrupter, themovable parts of which have a low moment of inertia to thus effect avery high opening accelerating movement of the movable contacts.Preferably, the construction is such that a plurality of seriallyrelated pressure-generating arcs are formed simultaneously with theestablishment of a plurality of serially related interrupting arcs, thepressure generated at the pressure-generating arcs being employed toeffect fluid fiow toward the interrupting arcs to effect the lattersextinction.

Further objects and advantages will readily become apparent upon areading of the following specification taken in conjunction with thedrawings, in which:

Figure 1 is an elevational view, partly in section, of a circuitinterrupter embodying my invention and shown in the closed circuitposition;

Fig. 2 is an enlarged fragmentary view, partially in section, of thelower portion of the lefthand arc-extinguishing assemblage shown in Fig.l, and taken substantially on the line II--II of Fig. 3, the parts beingshown in the closed circuit position;

Fig. 3 is a side elevational view, partially in section, taken along theline IIIIII of Fig. 2;

Figs. 4 through 20 show plan views of insulating plates used in theconstruction of the arc-extinguishing units shown in Fig. 1;

Fig. 21 is a View in section taken along the line XXL-XXI of Fig. 22;

Fig. 22 is a vertical sectional view taken through a modified form ofarc-extinguishing assemblage, the parts being shown in the closedcircuit position;

Fig. 23 is a view in section taken along the line XXIII-XXIII of Fig.24;

Fig. 24 is a vertical sectional view through a modified type ofarc-extinguishing unit;

Fig. 25 is a vertical sectional view taken through another modified formof arcextinguishing unit; and

Fig. 26 shows, in fragmentary manner, an operating arrangement for thecontact construction shown in Fig. 25.

Referring to the drawings and more particularly to Fig. 1 thereof, thereference numeral l designates a tank filled to the level 2 with asuitable arc-extinguishing fiuid 3, in this instance circuit breakeroil. Depending from the cover 4 of the tank I are two insulatingbushings 5, 6 through which extend terminal studs 1, 8. The terminalstuds 1, 8 have threadedly secured to their lower ends, respectively,contact feet 9, [0, the latter supporting identical arc-extinguishingassemblages generally designated by the reference numeral I l The twoarc-extinguishing assemblages II are electrically interconnected in theclosed circuit position of the interrupter, as shown in Fig. 1, by aconducting bridging member l2 which is reciprocally actuated in avertical direction by an insulating operating rod 13 which may beactuated by suitable mechanism, not shown.

Each of the arc-extinguishing assemblages ll comprises a plurality ofarc-extinguishing units generally designated by the reference numeral14, the construction of which is more clearly shown in Figs. 2 and 3.

It will be observed from aninspection of Fig. 1 that the conductingbridging member l2 during the closing operation slides betweendisconnect fingers 15 to strike a cross-member I6 composed of aconducting material. At the opposed outer ends of the cross-members 16are fixed insulating operating rods ll extending axially'of the arc--extinguishing assemblages I l. I 7

Referring to Fig. 3, it will be observed that the operating rods I? arepivotally connected at Hi to crank arms 19 which serve to rotate duringthe opening and closing operations a shaft 29 extending through each ofthe arc-extinguishing units [4 and on which is fixedly mounted abridging contact 2i electrically interconnecting two stationary contacts22, 23 associated with each arcextinguishing unit I4.

The bridging contact 2| has a contact portion 24 at one end and acontact portion 25 at its other or upper end; The contact portion 26separates from the stationary contact 23 to establish apressure-generating are indicated by the dotted line 26 of Fig. 3. Thecontact portion 25 separates from the stationary contact 22 to establishan interrupting are designated by the dotted lines 21'0f Fig. 3.Preferably, the stationary contacts 22, 23 are resiliently mounted bysuitable spring means, not shown, within the stationary contact housings28, 29 to provide the requisite contact pressure in the closed circuitposition, as shown in Fig. 3. Conductors 36 electrically interconnectthe lower stationary contact 23 of one unit I 4 with the upperstationary contact 22 associated with the immediately adjacent unit I4.

It will, therefore, be apparent that in the closed circuit position ofthe interrupter, as shown by the full lines in Figs. 1, 2 and 3, thatthe electrical circuit extending therethrough comprises terminal stud I,contact foot 9, stationary contact 22, bridging contact 2|, lowerstationary contact 23, conductor 30 through the next arc-extinguishingunit I l in like manner to finally conductor 3| which electricallyconnects the lower stationary contact 23 associated with the bottomarcextinguishing unit I l with the disconnect fingers 15. The electricalcircuit then extends through the conducting bridging member l2 andthrough the right-hand arc-extinguishing assemblage II in like manner tothe terminal stud 8.

Associated with each arc-extinguishing unit l4 are a plurality ofinsulating plates shown more clearly in Figs. 4 through 20. Eacharc-extinguishing unit I l comprises a cylindrical tube 32 composed ofinsulating material of the requisite mechanical strength. Disposedwithin the tube 32 is an insulating sleeve 33 which holds in position aplurality' of suitably shaped insulating plates to be hereinafterdescribed. The top insulating plate is designated by the referencenumeral 34 and has a configuration more clearly shown in Fig. 4 of thedrawings. The plate 34 has a plurality of apertures 35 through whichextend insulating dowel pins serving to hold the insulating plates inproper position with respect to each other. The plate 34 has anelongated aperture 36 formed therein through which extends partially theupper stationary contact 22 of the unit M. The upper portion of theleft-hand end of the aperture or slot 36 comprises a plurality ofpockets 3'! which serve to retain a plentiful supply of oil adjacent theinterrupting are 21. At the lower portion of the left-hand end of theslot is a restricted portion 38 into which the interrupting arc 2? mayenter only during relatively low instantaneous values of arcing current.Below the plate 34 is an insulating vent plate 39'having a configurationmore clearly shown in Fig. 5. The vent plate 39 has a widened slot 40which terminates in a vent opening 4!. Below the plate 39 is aninsulating plate 42 having a configuration as shown in Fig. 6. The plate42 has a slot 46 formed therein which communicates with a slot 44leading into a restricted portion 45.

Below the plate 62 is an insulating plate 46 shown more clearly in Fig.7. The plate 46 has a slot 41 which communicates with a plurality of, inthis instance six, pockets 48. Below the plate 26 is an insulating plate49 shown more clearly in Fig. 8. The plate 59 has a slot 55 whichcommunicates with a more restricted slot 5| lead ing at its left-handend to a plurality of, in this instance six, pockets 48. Below the plate49 is an insulating plate 52 having a configuration more clearly shownin Fig. 9. The plate 52ha's' a slot 53 formed therein which communicatesthrough a passage 5 to a restricted portion 55. Below the plate 52 is asecond venting plate 56 having a configuration more clearly shown inFig. 10, The plate 56 has a slot 51 formed therein which communicatesthrough a passage 58 to a vent opening 59.

Below the plate 56 is a plate 60 having a configuration more clearlyshown in Fig. 11. The plate 65 has a slot 6| which communicates througha passage 62 to a restricted portion 63. Below theplate 66 is a plate 64having a configuration more clearly shown in Fig. 12. The plate 64 has aslot 65 formed therein which communi- 'cates with a plurality of pockets66. Below the plate 64 is a plate 6'! having aconfiguratio'n, as shownin Fig. 13. The plate 61 has an enlarged portion 68 which communicatesby way of apa'ssage 69' to a restricted portion 7!). Below the plate 61is a third venting plate H having a configuration more clearly shown inFig. 14- of the drawings. The plate H has the enlarged portion 68 whichcommunicates through passage 69 to a vented opening 12. Below the plateH is a plate 13 having a configuration, as shown in Fig. 15. The plate13 has an enlarged portion 14 which communicates by way of a passage 15with a restricted portion 16.

Below the plate 73 is a plate 11 composed of insulating material andhaving a configuration more clearly shown in Fig. 16 of the drawings.The plate 11 has an enlarged portion 18 removed therefrom whichcommunicates by way of a passage 19. to a plurality of, in this instancesix, pockets 86. Below the plate H is an insulating plate 8| having aconfiguration more clearly shown in Fig. 17 of the drawings. The-plate8| has a portion '56 removed therefrom which communicates by way of apassage 82 to a plurality of, in this instance six, pockets 80.

Below the plate 8! is a plate 83 having a con figuration more clearlyshown in Fig. 18. The plate 83 has an enlarged portion 84 removedtherefrom which communicates by way of a passage 35'to a restricted stop86. Belowthe plate 83 is positioned a plate 8'! having a configurationmore clearly shown in Fig. 19. The plate 81 has an enlarged portion 88removed therefrom having a recess 89 at its left-hand end; The plate 81also has a portion 90 removed therefrom. The bottom insulating plate ofthe stack is designated by the reference numeral BI and has aconfiguration more clearly shown in Fig. of the drawings. The plate 9|has an enlarged beveled portion 92 removed therefrom through whichpartially extends the lower stationary contact 23 of the unit I4. All ofthe plates have the apertures 35 formed therein through which extendinsulating dowel pins holding the several plates in position.

The operation of the interrupter will now be explained. During theopening operation, the conducting bridging member I2 moves downwardly topermit a downward movement of the cross-member I6 and operating rod IT.The downward movement of the operating rods I'I causes acounterclockwise rotation of the crank arms I9 and hence acounterclockwise rotation of the bridge contact 2I to cause a separationof the contacts 22, and 23, 24. The separation of the contacts 22, 25establishes an interrupting are '21 and the separation between thecontacts 23, 24 establishes a pressure-generating arc 26. The pressurecreated at the pressure-generating are 25 causes oil to flow in thedirection as indicated by the arrows in Fig. 3 tending to bias theinterrupting are 21 into the restricted portions or restricted slotsafiorded by the plates 34, 42, 52, 60, 61, 13 and 83. During relativelyhigh instantaneous values of arcing current, that is, during 0 the peakof the alternating-current wave, the cross-sectional area of theinterrupting are 21 is too large to permit it to be forced by the oilfiow from the pressure-generating are 26 into the re- .stricted slots orportions formed by the aforesaid enumerated plates. It is only duringrelatively low instantaneous values of arcing current, that is near acurrent zero at a time suitable for interruption, that thecross-sectional area of the interrupting are 21 is sufiiciently small topermit the oil flow from the pressure-generating are 26 to force theinterrupting arc '21 into the aforesaid restricted portions or slots.While the interrupting are 21 is in these restricted slots, it issubjected to turbulence and deionizing activity as provided by the oilflow passing from the pressure-generating arc 25 through the severalvents to the region externally of the unit I4. Also, the interruptingare 21 engages a plentiful supply of oil retained in the pockets 31, 48,66 and 89 as an additional source of gas and deionizing turbulence. Theresult is an extinction of the interrupting are 21 at an early currentzero and the building up of sufiicient dielectric strength between theseparated contacts 23, 25 to prevent restriking.

It will be observed that the radius arm R between the upper movablecontact 25 and the shaft 20 is greater than the radius arm R between thelower movable contact 24 and the shaft 20. Consequently, by thisdifference in lever arm ratios, the speed of separation of the contacts22, 25 is greater than the speed of operation of the contacts 23, '24and the result is that the interrupting are 21 is rapidly lengthened toa considerable length. Also, by this construction, the length of thepressure-generating are 26 is controlled to prevent the attainment ofexcessive pressure thereat. Following interruption of the electricalcircuit through the interrupter, the movable bridging member I2separates from the disconnect fingers I5 to introduce two isolating gapsopening into the circuit, as indicated by the dottedlines in Fig. 1. v 7

"During the closing operation, the operating rod I3 moves upwardlycausing an engagement between the movable bridging member I2 and thedisconnect contacts I5 to cause thereby the raising of the cross-memberI6 and the operating rods I".-'. The raising of the operating rods IIcauses a clockwise rotation of the several crank arms I9 about theshafts 20 to thus cause a clockwise rotation of the bridging contacts 2|to effect a re-engagement between contacts 22, 25 and 23, 24. Theelectrical circuit is thencompleted through the interrupter.

The arc-extinguishing units I4 are maintained in spaced superimposedaxially aligned relation in a fixed manner by conducting supportsgenerally designated by the reference numeral 95. The supports 95 alsoserve to support the stationary contact housings 28 and 29.

Three of the units I4 serially connected interrupted currents from 500to 7000 amperes at 132 kv. with arcing times of only 1.2 to 1.9 cycleson 60 cycle circuits.

In the modification of my invention as shown in Figs. 21 and 22, thereis provided a modified type of arc-extinguishing unit generallydesignated by the reference numeral 91. Associated with the stationarycontact 22 of the upper arcextinguishing unit 91 in Fig. 22 and with thelower stationary contact 23 of the lower unit 91 are arcing horns 98jutting arcuately along the path of motion of the rotatable contact 2Ito which transfer of one terminal of the pressuregenerating arc 25 maybe efiected during highcurrent interruption to prevent the attainment ofexcessive pressure within the units 9'1. During low-currentinterruption, the length of the pressure-generating are 26 will besubstantially the same as the interrupting are 21, since the contactarms are equal in length for this modification, and the are 26 does nottransfer to horn 98.

However, during the interruption of high current, the ionized gas bubbleis suficiently large to engage the arcing horn 98, providing aconducting path thereto which results in the transfer of the upperterminal of the pressure-generating are 26 associated with the upperunit of Fig. 22 to the horn 98 to thereby shorten the length thereof.The length of the pressure-generating arc ZSduring high-currentinterruption is thus controlled to minimize the pressure formed thereat.As previously mentioned, during lowcurrent interruption the ionized gasformed adjacent the pressure-generating arc 26 is not sufficient tocontact the arc horn 98 to provide a conducting path thereto, and theupper terminal of the pressure-generating are 26 will remain fixed atthe stationary contact 22. Consequently, during low-current interruptionthe pressuregenerating arc 26 will extend and remain extended betweenthe contacts 22, 25 to attain a length practically the same as thelength of the interrupting arc 21. This considerable length attained bythe pressure-generating arc 2'5 during low-current interruption willserve to increase the pressure formed thereat; whereas duringhigh-current interruption the pressure-generating arc 26 will beshortened by transfer to the arcing horn 98 to minimize the pressureformed thereat.

If desired, magnetic means may be provided to bias thepressure-generating are 26 toward the arcing horn 98, which magneticbiasing means may be more effective during high-current interruptionthan during low-current interruption. The magnetic means which I providecomprises a U-shaped insert 99 composed of magnetic maas. n re. clea lyS own ff i fl p' i i i 1 f ,es the pressure-generatingrfilavto'iacilitatethe V alof the 'prcssureenerat n are 2,6. t "Eigs. 21and 22 alsqdisclose a piston arranga mer t asso iatedl'witnthe bridgingcontact 21 to facilitate lowcurren't interrupnen; The piston arrangementcorii'p 'se'san insulating block Hit extending betweenltwo insulatinglevers l9! having. their other ends. pivo'tally. mounted about acylindrical bearing'fl [12 haying a. hexagonal bore 'Ifhe'fhexagonalbqlf'joi the cylindrical bearing 1&2 isl'providedto accommodate'thehexagonal shaft C'e u tly; he nsu a leve s it: a free to rotate aboutthe cylindrical'bearings 5G2 rfigardless of the Qrientation of thebridging contact All Suitable biasing. means, not shown, such as springmeans encircling theQshaft 2;! may be provided to biastheinsulating'blo'clg. H33; away from. the contact 25. Thus theinsulating block mu associated withthe bottom. umber of Fig. 2 2 willbeheld in its'upper p ition as shown in the Q lb sedciricuit positicn ofth; nterrupter.

ost motijonponnection includes a pin i533 which. extends between twoinsulating levers Hit and travels in as qtl '14 Pr ded in h b d ncontact 2! to deterni e the tra fil of the insulating block I00,

Thefoperation oi the modified type of arc-extin'guishing. units9;"Lassociated with the modified type of arcextinguishirig f assemblageI05 shown in Fig. 22 will niowbe described. During the openingpperation'the insulating operating rod li moves downwardly, to} cause acounterclockwise rotation, oi the'bridging contacts 2| about the shafts29 to establish a pressureegenerating are 25 and an interrupting are 21,as previously described. In the. modified type of. arc-extinguishingassemblage 1H5, venting out of the units 91 takes placein an alternatemanner, that is, venting from theflowe'rmost. unit 9'! takes place tothe left and, ventin -I irem, he inunedia ely jacently disposedupward'unit 9] takes place to the right. This; alternate ventingarrangement from the assemblage I115 prevents a combining of the exhaustgasesfrom the several units 91 to minimize the hazard of high voltagebreakdown axially along the, assemblage 105. Also, unnecessay flowthrough, the stationary contact assemblages between" units isminimized,since the pressure is approximately balanced. between two adjacentpressurebreaksor between two adjacent interrupting breaks.

During low-current interruption, the pressure generated at; thepressureegenerating are 26 will be lower, and censeg'uently maynot besuflicient to send the requisitepilivelocity adjacent the interruptingarc 21 to "effect rapid extinction thereof. With the piston arrangementherein disclosed, the bridgingfcjont'act, 2l'will pick up the insulatingblock. M0 after approximately onethird of its rotativetravel to carrythe insulating block lei! with it and. thusslend oil-flow by pistonaction toward the interrupting are 21 to effect the extinction thereo f.During. high-current interruption, the pressure generated at the.pressure-generating arc. 26,.willbe sufiicient to maintain the blockHill in its extended position away from the bridging contact. 2|, andthe pressure generated at the pressure generating are 26 will actbetween the. block H19 andthe bridgingcontact It! to effect extinctionof. the interrupting w. i

again An additional function obtained by this piston arrangeinentis the"attainment of a'fiti sh tion that will force clean'oil' through the t?with each mechanical operation cf the I This flushing operationresultsing, in chanicaloperation of the breakerwithnocur nt passingtherethrough, that is, duringno -lo'ad eration. In other words, anopening stroke during such a mechanical no-load operation oi the breakerwill serve toicause the bridging member 2i to pick up the insulatingblock l'flll andfcause oil to now out of the vents "it in a manner simi;lar to low-current interruption; and oil will be drawn inthrough thecheck valve I501. During the closing stroke on such a mechanicalno-lo'ad'o eration of the interrupter, the insulating b we will bemaintained'in its extended posi en away from the bridging contact 2|.'As are ult during repeated opening and closing noloafd p; erations ofthe interrupter oil is drawn in through the check valves E0? and forcedby piston ac tin through the unit 9? and out the Vents 106,

In the modified type of arc-extinguishing unit generally designated bythe reference gar and shown in Figs. 23 and 24, I have'pro; vided anarcing horn H18 disposed at the upper end the unit 508 and a secondarcing, horn is disposed at the lower end of said unit," can; se uentiy,the pressure-generatingfarc 26- ma along the bridging contact 2| and thearcing horn $55. In like manner, the interrupting may run along thebridging contactfz l and the upper arcing hornj I09. Preferably,magnetio means are provided to bias the interruptin'gfarc 2's laterally.The magnetic means which IutiliZfe comprises a U-shaped insert'lllcomposed of magnetic material, in this instance iron.

By providing a construction wherein'both the pressure-generating arc 26and the. interrupting are 2'! may move laterally, fresh oil is engagedby both of said. arcs, interruption is facilitated and erosion of thefibreplates minimized. One or. more of the U-shaped inserts Illv used inthe unit we maybe used in conjunction with them;- te'rrupting' structureshown in Figs. 2 and 3th facilitate the lateral movement of theinterrupt} ing. arc 27 in the'unit's l4 toward the. restricted portionsof the slots; however, this constructicn of utilizing magnetic means isnot shown in'Figfs. 2 and 3. V i V Fig. 25 shows a modified type ofcontact con,- struction associated with a modified type (ii are;extinguishing unit generally designated by'the reference numeral H3. Inthis modified typeof construction, I utilize a first bridging contact iHi and a second bridging contact H5 which do} operate together, tobridge the stationaryf'contacts 22, 23. An operating arrangement for thefirst and second bridging contacts I l4, [l5 may assume a form as shownin Fig. 26 of the draw ings. In this operating arrangement, theop'erai'a irig rod l? is' pivotally connectedat 18 to a crafik arm l9serving, to rotate a, piniongear, H5, gear H6 meshes with gears H1, H8whicHrotate shafts 58,126. The shafts 1 i9, l2ll serve re terate thefirst and second bridging contacts H4} H5 in the desired direction. Thefirst and second bridging contacts H 6 i5 have cooperable contactportions lZI, l22 which, when separatedf lish a pressure-generating arc.26. Each brrd ng contact li t, H5 separates from the stationary contacts22, 23 to establish thereby twoin writing arcs 2?. Pressure generat'edattrie gle pressure-generating are 26 facts in thedire n i ated by therews' ig.- fite "extinction of the two interrupting arcs 21 at thesplitters I23 associated with the vents I24.

It will be observed that this construction shown in Fig. 25 attainsmaximum break distance in a rotating contacts H4, H is somewhat lessthan .ments of my invention that from the point of View of avoidingrestriking or voltage breakdown, the construction is particularlyadvantageous since there are no overlapping potentials in the voltagegradient from one end of the multibreak arc extinguishing assemblage tothe other. Furthermore, the stationary contacts are easily accessibleand the movable contacts require no shunts at all. By employingdifferent lever ratios the length of the pressure break distance to theinterrupting break distance may be easily varied by changin the pivotlocation on the bridging contacts 2|. It will be apparent from theforegoin description that the inertia of the rotating members isconsiderably reduced over conventional structures, and that the breakdistance is a maximum in the open circuit position with a minimumoverall length of the assemblage. Also, I have shown both magnetic meansand piston means for speeding up low-current interruption where thepressure generated at the pressure-generating arc is relatively low.

Although I have shown and described specific structures, it is to beclearly understood that the same were merely for the purpose ofillustration and that changes and modifications may be made by thoseskilled in the art without departing from the spirit and scope of theappended claims.

I claim as my invention:

1. In a circuit interrupter, a stationary arc extinguishing assemblageincluding a plurality of stationary spaced axially aligned seriallyrelated arc extinguishin units, each unit being substantially enclosedto form a pressure-generating chamber and an interrupting chamber, meansventing the interrupting chamber only laterally of the unit whereby theupper and lower ends of each unit are substantially closed, relativelystationary contact means for each unit including a pair of relativelystationary contacts disposed at the upper and lower ends of each unit, arotatable shaft fixedly positioned intermediate the upper and lower endsof each unit so as to be spaced axially between the pair of stationarycontacts, a lever-shaped bridging contact member for each unit mountedintermediate its ends upon the shaft, the bridging contact memberestablishing a pressure-generating are adjacent one end thereof withinthe pressuregenerating chamber, the bridging contact being cooperablewith at least one of the stationary contacts to establish aninterrupting are adjacent the other end thereof within the ventedinterrupting chamber, disconnect means disposed adjacent one end of thestationary arc extinguishing assemblage including a movable disconnectmember and a relatively stationary disconnect contact, an operating rodextending axially externally of the units, means connecting one end ofthe operating rod to the relatively stationary disconnect contact, andmeans operatively connecting the operating rod to each of the rotatableshafts to simultaneously effect their rotation.

2. In a circuit interrupter, a substantially enclosed arc extinguishingunit defining a pressuregeneratin chamber and an interrupting chamher, arelatively stationary contact, a pair of lever-shaped movable contactmembers, a pair of rotatable shafts, each lever-shaped movable contactmember being mounted intermediate its ends upon a rotatable shaft, meansfor simultaneously rotating the shafts in the same direction, theopening separating motion of one movable contact member establishing apressuregenerating are adjacent one end thereof within thepressure-generating chamber and an interrupting are adjacent the otherend thereof within the interrupting chamber, and fluid flow passagemeans interconnecting the two chambers so that fluid under pressure fromthe pressure-generating arc may flow through the passage means into theinterrupting chamber to effect the extinction of the interrupting arctherein.

3. In a circuit interrupter, an arc extinguishing unit defining a pairof interrupting chambers positioned adjacent opposite ends of the unitand a pressure-generating chamber disposed intermediate the ends of theunit, a pair of stationary contacts disposed in the interruptingchambers, a pair of rotatable shafts disposed in axially alignedrelation with respect to the two stationary contacts, a pair ofelongated movable contact members mounted intermediate their ends uponthe pair of shafts, each movable contact cooperating with a stationarycontact to establish an interrupting are within an interrupting chamber,and the two movable contacts cooperating with each other to establish apressure-generating arc within the pressure-generating chamber.

4. In a circuit interrupter, an arc extinguishing assemblage including aplurality of spaced arc extinguishing units disposed in axially alignedrelation, each unit being substantially enclosed and defining a pair ofinterrupting chambers disposed at the upper and lower ends of each unit,laterally leading venting means for each interrupting chamber so thatthe two interrupting chambers vent in opposite directions laterally outof the unit, the unit also defining a pressure-generating chamberpositioned intermediate the ends of the unit, a pair of stationarycontacts disposed in the two interrupting chambers of each unit, a pairof shafts for each unit, a pair of elongated movable contact membersmounted intermediate their ends upon the pair of shafts in each unit,each movable contact cooperating with a stationary contact to establishan interrupting are within an interrupting chamber, the two movablecontacts cooperating with each other to establish a pressure-generatingare within the pressure-generating chamber of each unit, passage meansleading from the pressure-generating chamber of each unit toward bothinterrupting chambers, and means for simultaneously rotating the shaftsof all the units to thereby simultaneously establish a plurality ofpressure-generating arcs and a plurality of interrupting arcs within theassemblage.

5. In a circuit interrupter, means defining a stationary substantiallyenclosed arc extinguishing unit, a pair of stationary contactspositioned at the upper and lower ends of the unit, the unit forming apressure-generating chamber adjacent one stationary contact and aninterrupting chamcontacting engagement with the two stationary=contacts, means for rotating the shaft and movable contact member sothat the ends thereof separate substantially simultaneously in oppositedirections from the two stationary contacts to simultaneously establisha pressure-generating arc-within the pressure-generating chamber and aninterruptingarc within'the interrupting chamber, and liuid'fiow passagemeans interconnecting the two chambers.

6. 'In a circuit interrupter a stationary arc extinguishing unit havingthetop and bottdm'thereofsubstantially closed, a pairof stationarycontacts -positionedadjacent the top-and bottom of the unit, a rotatablymounted movable levershaped contact member positioned intermediate theends of the unit with'the ends thereof making'contacting engagement withthe stationary contacts intheclosed circuit position of the interrupter,the unit defining a pressure-generating chamber adjacent one stationarycontact and an interruptingchamber adjacent the other stationarycontact, laterally extending venting means leading laterally out oneside end of the unit from the interrupting chamber, means for rotatingthe movable contact so that the ends thereof separatesimultaneously inopposite directions from the stationary contacts'to establish apressure-generating are within the pressure-generating chamber and aninterrupting are within the'interruptingchamber,-a pair of'laterallyextending arc horns positioned adjacent the "two stationary contacts,magnetic means for biasing the interrupting are along one-of thea'rci'ng horns towardthe venting means, and fiuid'flo'wpassage meansinterconnectingthetwo chambers.

'7. ha circuit interrupterof the liquid break 2 type a substantiallyenclosed arc extinguishing unit "submerged in a-suitable arcextinguishing liquid, a pair of stationary contacts positionedadjacent'opposite ends of theu'nit,*the-unit defining apressure-generating chamber adjacent one stationary contact andanlnterrupting chamber adjacent the otherstationaryc'ontact, a rotatableshaft positioned intermediatetheends of the unit, a movable levershaped'contact mounted intermediate 'its ends-upon the shaft and'havingthe end portions thereof making contacting engage meet it e We Stati nabeta s' 4th? closed circuit position" of the interrupter, means forrotating the shaft and m'ovable' conta'ct'to establish apressurekg'enerating arc within the pr s en atin rhamb a d a inte ruptig are within the interrupting chamberffiuid "flow passage "meansinterconnecting the "two chambers, a'pistonmemberloosely mounted upontheshaft, anda 1p t motion connection between the piston member and themovable contact.

8 In a circuit interrupter a stationary arc extinguishing assemblageincluding :a plurality of stationary axially aligned are" extinguishingunits disposed in spaced end-to endrelationship, a rb Stationary O a9tsmipn s1 a ent the opposite axial endsof-each unit, a rotatable Sha t x nn t o h a h u n e mediate he en s there a lev mshaned m vable contactmember disposed-interiorl'ywithin each unit and means operativelyconnecting the rod means externally-of the unit with each I rotatableshaft "to cause their simultaneous operation.

9. In a circuit interrupter, a stationary arc extinguishing assemblageincluding a plurality of stationary axially aligned arc extinguishingunits disposed in spaced en'd-to-e'nd relationship, :avpair'ofstationary contacts positioned adjacent the opposite axial ends of eachunit, the "unit defining a pressure-generating chamber adjacent onestationary'contact and an interrupting chamber'adjacen't theotherstationariy contact,

a rotatable -shaft extending through each unit intermediate the endsthereof, a lever-shaped movable contact member disposed 'interiorlywithin each unit and mounted intermediate its ends upon the rotatableshaft,'the end portions of each movable contact member m-akingcontactingengagement with the stationary contacts of the respective unitgthe.rotati'onof the shaft causing the ends of the movable contact member toseparate simultaneously in oppcsite'directions fromthe respective twostationary contaots of-the particular unit to es tablish simultaneouslya p ssu er ener tine ar w thin t e p e Vgener ating chamber and=interrupting arc W h n t e inter u tin h m r. peratin od meansextending axially externally of the units q cau -a tua i 0 thesemblaeexand means Weill e1 qn e t n th e mea sx a ly of the unit witheach rota-tableshait to-cause their simultaneous operation.

10. In a circuit interruptena stationary arc extinguishing assemblageincluding a plurality of stationary axially aligned arc extinguishingunits disposed inspaced end-to-endrelationship, a. pair'of stationarycontacts positioned adjacent the opposite axial ends of each unit, onecon:- tact being on ahigher level of the assemblage than the 'o't'hercontact, a rotatable-shaft associated with each unit, am'ovable bridgingcon: tact mounted intermediate its ends upon the shaft to electrically"interconnect the two sta: tionary contacts, each unit'defining asubstam tially confinedlpressureTgenerating chamber ad: jacent onestationary contactanda vented in: t r ptie c mbe a a e tath s arycontact, passage means extending between the two chambers, the movablebridging contact ep ra om ne s t o ery ont ct to tab: lish apressure-generating arc axially of the as; semblage within thepressure-generating cham: her and from the other stationary contact toestablish an interruptingarc axially ofthe as; semblage within theinterrupting chambenand means including an elongated operating rodmovable axially of the assemblage for simul: taneously rotating all theshafts of the as, semblage. M

i1. In a circuit interrupter, a stationary are extinguishing unit,a'pair of stationary contacts disposed at opposite endsof the unit, theunit defining a substantially confin d lir ssure generat: ns ch m e aqiaent on t tionary rs cnt ct and a vented interrupting chamber adjacentthe other stationary contact, a rotatable shaft, a movable lever-shapedcontact member mounted intermediate its ends upon the shaft, the movablecontact separating from one stationary contact to establish apressure-generating are within the pressure-generating chamber, themovable contact separating from the other stationary contact toestablish an interrupting arc within the interrupting chamber, passagemeans interconnecting the two chambers, and a stationary arcing horndisposed adjacent to the stationary pressure-generating contact andjutting arcuately along the path of motion of the movablepressure-generating contact in closely spaced relationship therewith foran appreciable length of travel of said pressure-generating contact towhich one terminal end of the pressuregenerating arc may transfer onlyduring high current interruption.

12. In a circuit interrupter, a substantially enclosed arc extinguishingunit defining a pressure-generating chamber and an interrupting chamber,a relatively stationary contact, a pair of lever-shaped movable contactmembers, a pair of rotatable shafts, each lever-shaped movable contactmember being mounted intermediate its ends upon a rotatable shaft, meansfor simultaneously rotating the shafts in the same direction, theopening separating motion of one movable contact member away from theother movable contact member establishing a pressuregenerating areadjacent one end thereof within the pressure-generating chamber, theopening separating motion of the first-mentioned movable contact memberaway from the relatively stationary contact establishing an interruptingare adjacent the other end thereof within the interrupting chamber, andfluid flow passage means interconnecting the two chambers so that fluidunder pressure from the pressure-generating arc may flow through thepassage means into the interrupting chamber to effect the extinction ofthe interruptin arc therein.

13. In a circuit interrupter, an arc extinguishing assemblage includinga plurality of stationary substantially enclosed arc extinguishingunits, a pair of stationary contacts positioned at the upper and lowerends of each unit, each unit forming a pressure-generating chamberadjacent one stationary contact and an interrupting chamber adjacent theother stationary contact, the upper and lower ends of each unit beingsubstantially closed, laterally extending venting means leading from theinterrupting chamber of each unit laterally out one side end of theunit, a rotatable shaft disposed intermediate the ends of each unit, alever-shaped movable contact member mounted intermediate its ends uponthe shaft and having its ends making contacting engagement with the twostationary contacts, means for rotating the plurality of shafts andmovable contact members in unison so that the ends of the severalcontact members separate substantially simultaneously in oppositedirections from the stationary contacts to simultaneously establish aplurality of pres sure-generating arcs within the pressure-generatingchambers and a plurality of interrupting arcs within the interruptingchambers, and fluid flow passage means associated with each areextinguishing unit interconnecting the pressuregenerating andinterrupting chambers of that unit.

14. In a circuit interrupter, an arc extinguishing assemblage includinga plurality of stationary substantially enclosed arc extinguishingunits, a pair of stationary contacts positioned at the upper and lowerends of each unit, each unit forming a pressure-generating chamberadjacent one stationary contact and an interrupting chamber adjacent theother stationary contact, the upper and lower ends of each unit beingsubstantially closed, laterally extending venting means leading from theinterrupting chamber of each unit laterally out one side end of theunit, a rotatable shaft disposed intermediate the ends of each unit, alever-shaped movable contact member mounted intermediate its ends uponeach shaft and having its ends making contacting engagement with the twostationary contacts of the respective unit, an operating rod extendingaxiall of the units for rotating the several shafts and the severalmovable contact members so that the ends of the movable contact membersseparate substantially simultaneously in opposite directions from thestationary contacts to simultaneously establish thereby a plurality ofpressure-generating arcs within the pressure-generating chambers and aplurality of interrupting area within the interrupting chambers, andfluid fiowpassage means stationary contact and an interrupting chamberadjacent the other stationary contact, the upper and lower ends of eachunit being substantially closed, laterally extending venting meansleading from the interrupting chamber of each unit laterally out oneside end of the unit, a rotatable shaft disposed intermediate the endsof each unit, a lever-shaped movable contact member mounted intermediateits ends upon each shaft and having its ends making contactingengagement with the two stationary contacts of the respective unit, anoperating rod extending axially of the units for rotating the severalshafts and the several movable contact members so that the ends of themovable contact members separate substantially simultaneously inopposite directions from the stationary contacts to simultaneouslyestablish thereby a plurality of pressure-generating arcs within thepressure-generating chambers and a plurality of interrupting arcs withinthe interrupting chambers, fluid flow passage means associated with eacharc extinguishing unit interconnecting the pressure-gencrating andinterrupting chambers of that unit, disconnecting means disposedadjacent one end of the arc extinguishing assemblage including a movabledisconnect member and a relatively stationary disconnect contact, meansconnecting one end of the operating rod to the relatively stationarydisconnect contact, and means operatively connecting the operating rodto each of the rotatable shafts to simultaneously effect their rotation.

16. In a circuit interrupter, a stationary arc extinguishing assemblageincluding a plurality of stationary axially aligned arc extinguishingunits disposed in spaced end-to-end relationship, a pair of stationarycontacts positioned adjacent the opposite axial ends of each unit, arotatable shaft extending through each unit intermediate the endsthereof, a lever-shaped movable contact 15 memben disposecb interionlywithinzeach: unit: and: mcuntemintermediat'e its endsiuponthe: rotatableREFERENCES CITED The following references areof record in the me ofpatent: 25;

PA EENTST- shaftutha end, portions of; each-imovablecontacti ggig pimemben'making-'contactingiengagement withithe 4902746 Gibbs f istationary contacts; of the: respective unit, the 5* 12092792 Young 1rotation of theshaftcausingthe'endsofithe mov- .2 6 Lotz able contact.member to: separate simultaneously 2 6 1929 in: 01213051178: directionsfrom; the respective; two 5 1 m j 2671931 stationary contacts-0f theparticular unit, opei f i Austin i f 1932; ating; rod means extendingaxially externally-01:10; Trenchglg a. 't' f the: units: to causeactuation: of? the assemblage; 3 1 Baker, 1934; disconnect meansdisposed adjacent one end. of: f' i Erben NOV'V the; arc extinguishingassemblage including. a: ,10 f' j 1937; movabie disconnect member andarelatively; sta,-- 3 c i tinnary disccnnectcontact,,means connectingone:3 f Dyer end of: the operating. rod meansto the relatively 1 3 g b.1946; stationary disconnect contact, and means opera/ tivelyr connectingthe rod meansexternally of the; FOREIGN. PATENTS unit? i:With: eachrosatableshaft to cause their: Number country. Date, Simul51118011509812 im 20: 365,296 Germany Dec: 14; 1922' WINTHROP LEEDSsoewee Fi'an'ce Dec, 3-, 1 936

